1. Field of the Invention
The present invention relates generally to child resistant safety buckles used with a strap, and relates more particularly to the structure and materials used to form child resistant safety buckles for securing a child in a seat.
2. Description of the Related Art
Child safety buckles are used in a number of child restraint applications including securing children in strollers, high chairs and shopping carts. Child restraints contribute to securing a child in a seat to prevent the child from being free and thus avoid situations in which the child might be in danger or injured. A prior art buckle 25 with a male part 20 and a female part 30 for use in a seatbelt assembly is illustrated in FIGS. 1a and 1b. Buckle 25 has two arms 10 on male part 20 that slide into a slot 12 of a female part 30. Barbed ends 14 of arms 10 engage shoulders 15 in female part 30 when buckle 25 is clasped. Buckle 25 can be manipulated by some young children to unclasp the buckle. As is well known, buckle 25 is unclasped by pressing together or pinching barbed ends 14 toward each other until free of shoulders 15. Once ends 14 are free, male part 20′ can be removed from female part 30.
A particular type of safety buckle is child resistant, to prevent children under a given age from releasing the buckle and freeing themselves. Although children under a certain age are prevented from unclasping the buckle, adults typically have no difficulty in disengaging the buckle to free the child. One type of buckle that is child resistant but can be opened by an adult has a double action feature to permit the buckle to be opened. That is, the buckle is opened by operating several disengaging elements to unlatch the buckle and disengage the buckle portions. By providing two actions to allow the buckle to be opened, the buckle is made child resistant, because a typical child under a certain age is unable to properly operate the two features, either sequentially or at the same time, for example, to unlatch and open the buckle. At the same time, an adult can easily and intuitively disengage the buckle by operating the two features as required.
A number of buckles are available that, while not designed to be child resistant, do have security features, so that the buckles will not disengage unexpectedly. These types of buckles also have a multi-open feature, in that a number of operations are conducted on the buckle to permit the buckle to be unlatched and opened. Typical applications for these types of buckles involve heavy duty or industrial uses, such as clasps for utility belts, sportswear or other applications where the buckle is subjected to high loading or must be well secured.
One such high security buckle is shown in U.S. Pat. No. 5,774,956 to French et al., which discloses a buckle with flexible side release latches and a third latch accessible on the front of the buckle. The male portion of the buckle includes a central latch arm that engages the female portion of the buckle in a central portion, and is released by pressing on a central button on one side of the female buckle portion. The buckle unlatches when both side latch arms are moved inwardly, and the central arm is moved away from the catch on the female portion. The buckle unlatches when all three arms are moved to unlatched positions simultaneously. Changing the orientation of the male portion when inserted into the female portion results in the central arm catch being defeated, because there is no corresponding catch cooperation on the back side of the female.
U.S. Pat. No. 5,991,985 to Galbreath discloses a safety buckle (the '985 buckle) with side catch arms and a central catch that engages with a depressible button catch on the female portion of the buckle. To disengage the buckle, the central button on the female portion of the buckle is depressed to either disengage from the central arm or displace the central arm to disengage from a catch. If the male portion of the buckle is inserted into the female portion of the buckle in an opposite orientation so that the central arm does not engage the depressible button catch, the buckle either does not clasp or the central arm does not latch.
U.S. Pat. No. 6,311,374 to Anscher shows a two-operation buckle (the '374 buckle) with a center arm that includes a push button near the base of the male member with a catch near the push button to engage an opening catch in the female member when the buckle portions are engaged. In addition, the buckle is non-reversible, i.e., if the male member is inserted in an opposite orientation, so that the push button faces the back of the buckle assembly, the male and female members do not engage with each other.
U.S. Pat. No. 6,684,466 to Nishida et al. shows a two-operation safety buckle in which the male member has a center arm with a catch recess that engages a catch on the female member. The center arm of the male member is displaced downwardly during insertion to permit the latch member to protrude into the latch recess when the male member is fully inserted and the center arm returns to its undisplaced position. The center arm is disengaged from the catch with a button on the female member that is pressed to displaced the center arm away from the catch of the female member, so that the male member can be withdrawn from the female member, with the sidearms being depressed together. This buckle configuration is not reversible, in that if the male is inserted in an opposite orientation, the center arm does not latch with the female latch member. Due to the shape of the buckle components, high stress environments may have a further adverse impact on the buckle. For example, if the buckle deforms, a situation where the buckle can be clasped but not unclasped may occur.
U.S. Pat. No. 6,138,330 (the '330 patent) to Galbreath discloses a two-operation safety buckle in which the sidearms of the male member are prevented from being squeezed together to unlatch the buckle, when the male and female members are engaged together. A blocking device in the female member engages with the latching arms of the male member to prevent their displacement and thus prevent them from being unlatched until the blocking device is displaced away from the latching arms to permit their relative movement. Accordingly, the blocking device is first displaced, and then the arm latches are displaced towards each other until they are free of their respective latches in the female member, at which point the male member can be withdrawn from the female member. The configuration of this buckle permits the male member to be inserted in the female member in an opposite orientation. The blocking device and arm latching functions of this buckle are not independent of each other when the buckle is in a clasped condition. The arms are prevented from being operated due to the blocking device, which is first displaced away from the arms before they may be operated. The sequential operation to unblock the arms represents a major departure from other conventional buckles where the latching mechanisms are independent in the clasped condition. This difference is significant to operation in a commercial environment where buckles are subject to forces that routinely alter their shape. Even slight forces may deform a given buckle, resulting in the buckle being prone to jamming.
Moreover, the buckle of the '330 patent is difficult to manufacture due to practical tolerance limitations in the materials and the amount of area within the confines of the buckle interior. In addition, the buckle configuration is not designed to withstand high impact or compressive forces that are typically encountered in safety buckle applications. The combination of small manufacturing tolerances and lack of resilience to environmental factors contribute to operational problems. For example, small changes in tolerances due to impact or compressive forces, or through extreme temperature ranges, may influence operation of the blocking device leading to buckle failure. The buckle material can exacerbate the above challenges when an inexpensive or typically brittle material such as acetal or nylon is used.
A particular failure mode that is highly undesirable occurs when the deformed buckle can be easily clasped, but becomes extremely difficult to unclasp. Often, such failed buckles may respond to the application of brute force to be opened, such as the application of a high tensile force or prying force. However, a buckle with a blocking action typically does not respond to brute force methods to open the buckle due to the particular nature of the blocking mechanism design. In such a situation, the belt attached by the buckle is cut away to free the occupant, destroying the usefulness of the belt and buckle.
In each of the above two-operation safety buckles, a change in the shape of the male or female member may cause the buckle either not to clasp, or to clasp with great difficulty or produce the problematic possibility that the easily clasped buckle may not easily unclasp. In a case of the '330 patent to Galbreath, there are challenges to making the buckle impact resistant or durable in stressful environments to avoid changes in shape. For example, if the buckle becomes deformed due to impact or compression, it is extremely difficult to unlatch the buckle.
Indeed, conventional buckles are often made with materials that are inexpensive to avoid increased costs for the buckle components and seatbelts overall, for example. Low cost materials, such as acetal, tend to be brittle and somewhat inflexible, and the structural elements tend to be more difficult to operate. Accordingly, the structural elements that are manipulated to operate the buckle are minimized to maintain the operational characteristics of the buckle and permit the structural elements to be more easily operated. However, this minimization tends to limit the operational robustness of the manipulated structural elements. Accordingly, buckle types like that illustrated in FIGS. 1a and 1b have diminished usefulness in child restraint applications due to rapid failure in practical applications when composed of less robust materials.
The challenges noted above become particularly difficult in applications involving child resistant safety buckles in seatbelts for children. Specifically, shopping cart seat belts for children are subjected to extreme environmental conditions including wide variations in temperature and humidity, direct sun, snow, ice, high impact and compressive forces, and so on. The importance of providing a child resistant buckle, however, prompts the desire to overcome these challenges, and provide a buckle that is not easily opened by children under a certain age. For example, the child restraint should not be defeated by a child 4 years or 48 months old, and should be capable of being readily opened by adults or older minors, for example, of 16 years of age or older. Indeed, a standard for child resistant child restraints is available to help manufacturers and suppliers reach this goal. However, the challenges of maintaining child resistant features in extreme application environments remain.
When the types of buckles and straps described above are used in an environment where the buckles are typically subjected to high impact and compression forces, the buckle can be damaged. When child resistant buckles and straps are used as child safety restraints on grocery shopping carts, for example, the design and functionality of the buckles is severely tested. When carts are nested together with one another for storing large numbers of carts easily, for example, the buckles can be caught between the carts and can be subjected to high impact and compressive forces. Impact forces like these tend to cause the buckles to crack or even shatter. Compressive forces can deform the buckle beyond a point of elastic resilience, resulting in an unworkable buckle.
In addition, the seatbelt assembly is sometimes misused in connecting grocery carts together, for example, to tow a number of carts all at once. These occasions of misuse can produce high tensile strain on the buckle, causing the buckle to fail and resulting in damage to buckle components.
It would be desirable to obtain a child resistant buckle, that has a design or structure that can take advantage of selective materials to be robust under extreme conditions. functions.